1. Field of the Invention
This invention relates to coprecipitated cobalt-silica catalysts and their use in hydrogenating organic compounds. In one aspect, this invention relates to the preparation of supported coprecipitated cobalt-silica catalysts. In another aspect, this invention relates to the use of the catalysts, in reduced form, to hydrogenate organic compounds.
2. Description of the Prior Art
The catalytic reduction of organic compounds in the presence of nickel and cobalt catalysts is known. Nickel catalysts, especially supported nickel catalysts, have many commercial uses. For example, U.S. Pat. No. 3,535,271 teaches the use of a nickel catalyst promoted by copper for dehydrogenation, cracking, reforming, polymerization, isomerization, alkylation, as well as other treating processes. Other examples of nickel catalysts and their use in reforming and other processes include U.S. Pat. Nos. 2,750,261; 3,205,182; 3,351,566; 3,417,029; 3,697,445; 3,859,370; 3,868,332; 4,088,603; 3,417,029; and Belgium Patent No. 841,812 (which generally corresponds to U.S. application Ser. No. 577,328). In all of these patents, the catalysts are prepared by coprecipitation or impregnation processes wherein the catalytic metal precursors are either precipitated from solution in the presence of a support material or solution containing said precursor or impregnated into the pores of a porous support material. In the British Patent No. 1,220,105, for example, aqueous solutions are employed in conjunction with a homogeneous precipitation procedure to give highly dispersed nickel catalyst.
D. J. C. Yates, W. F. Taylor and J. H. Sinfelt (J. Am. Chem. Soc., 86, 2996 [1964]) described a chemisorption technique and its utility in correlating nickel particle size (and/or nickel surface area) with catalytic activity. In FIG. 3 of their publication, there is shown that a direct relation exists between reduced nickel surface area (m.sup.2 /g of catalyst) and initial reaction rate for ethane catalytically converted into methane (as mmoles C.sub.2 H.sub.6 converted per hour per gram of catalyst). It follows, then, that methods which increase the nickel surface area of a nickel catalyst (other factors such as nickel content remaining constant) is a desirable feature, leading to a catalyst of improved catalytic activity. Patentees of U.S. Pat. Nos. 3,697,445; 3,859,370 and 3,868,332 also appreciated that by achieving a higher degree of dispersion of nickel in the catalyst results in a more active catalyst and indeed they obtain a fairly high degree of dispersions by their coprecipitation techniques wherein nickel cations were gradually precipitated from an aqueous solution in the presence of silicate anion and solid porous particles to obtain dispersion greater than 70 m.sup.2 /g of reduced nickel metal per gram of catalyst. Belgium Patent No. 841,812 teaches that the addition of copper ions during the precipitation step provides a catalyst that can be reduced at temperatures of approximately 200.degree. C. U.S. Pat. No. 4,088,603 discloses an improved method of activating the coprecipitated nickel-copper-silica catalysts.
A number of patents have disclosed cobalt, cobalt-nickel and cobalt-nickel-copper catalysts, e.g., U.S. Pat. Nos. 3,166,491; 3,385,670; 3,432,443; 3,547,830; 3,650,713; 3,661,798; 3,945,944; 4,014,933 and 4,026,823; and British Patent Nos. 1,000,828; 1,000,829; 1,095,996; 1,095,997 and 1,182,829. None of these patents, however, disclose coprecipitation of cobalt salts and silicate ions in the presence of the porous carrier particles.
In some of the above-mentioned patents, for example, U.S. Pat. Nos. 3,697,445; 3,859,370; 3,868,332 and Belgium Patent No. 841,812 it is mentioned that cobalt or iron may be used in place of nickel in the coprecipitation process. However, these patents only show nickel (in the examples) as the non-noble Group VIII catalytic metal used.